mike-hr Posted March 20, 2009 Share Posted March 20, 2009 I would like some feedback on this. I recently told a fellow that the only reason not to have a blower-type forge, is if he had no electricity to run a blower. Farriers, sure, but driveway smiths have acess to extension cords. I see the majority of people starting up with gas forges here are constantly fiddling with flame adjustment on Venturi type forges. I forge Semi-professionally, as do a lot of the folks I hang out with. We all have blower gas forges, along with solid fuel stations. I see it as advantageous to be able to adjust the gas flame from neutral, for heavy production runs, to rich, for detailed, less scaley work, by fiddling with the air intake adjustment from the blower. This takes less than two seconds on my blower forge. I would postulate that a person can make any one of a dozen burners for a blower forge, and be able to adjust it to rich, neutral, or lean, in a couple of seconds. As a matter of discussion, why do most folks start with venturi-type burners? In my opinion, they are NOT the easiest way to start out. mike Quote Link to comment Share on other sites More sharing options...
Brian D Posted March 20, 2009 Share Posted March 20, 2009 Mike, I disagree with some of the things in your post. First, what is the ultimate goal of the burner? I would think one would attempt to get the maximum BTU out of a given amount of gas going through the burner at any given time and achieve forging and welding temps....Right? In other words, efficient operation at a target BTU range. If a burner is designed and tuned properly, it can be very efficient in a naturally aspirated state. (non-blower) I can induce enough oxygen in the environment at my burner nozzle that the mixture will not burn properly. (too lean) I can also on the other side of the spectrum choke the air intake down to create a very rich mixture. In simple terms, a properly designed and carefully tuned burner can be made very efficient and easy to achieve different temperatures and lean / rich environments by simply adjusting air choke, and gas pressure. If folks are having to fiddle more than that to get the burners to perform, the burners are not designed and tuned properly. I have not personally tested this, but I dare say that If I hooked up a forced air blower system to my current burners, I would not get much more heat (efficiency) out of my burners. (if any at all) But I would be adding some more complexity to my current burner system. Quote Link to comment Share on other sites More sharing options...
Fe-Wood Posted March 20, 2009 Share Posted March 20, 2009 I like naturally asperated burners because they are quieter and I think as adjustable or more than power assist. After being tuned right, its easy to get the required flame type. For one, It dosn't seem like a power blower can be idled like a naturally asperated one. Actually, I've never used and blower type forge. I've only used a blower type furnace for casting and it had its issues too. Casting when the power went out one day was a real drag. One of my next projects, after I get a good burner design is a naturally asperated furnace for a #8 or 10 Crucible. Quote Link to comment Share on other sites More sharing options...
mcraigl Posted March 20, 2009 Share Posted March 20, 2009 Brian, Where in Northern Utah are you at? I grew up in Randolph, and I bet you money you can't make a naturally aspirated burner get to welding heat there. You probably can a blown burner though. I'm Hoping that someone with both types will jump in here and tell us when/why they like to use one over the other. ML Quote Link to comment Share on other sites More sharing options...
brucegodlesky Posted March 20, 2009 Share Posted March 20, 2009 mcraigl, you'll lose that bet. I went to forced air to save money on fuel. I'd just as soon use aspirated when simply forging. When it comes to welding damascus, forced air can't be beat. Heat and lots of it very fast. As a matter of fact, I was checking out Jymm Hoffmans burners this week and think I'm going that route. Quote Link to comment Share on other sites More sharing options...
Brian D Posted March 20, 2009 Share Posted March 20, 2009 I am in a town called Hooper. (Due west of Ogden, right before you get to the lake) I know Randolph pretty well, I have spent a lot of time there and in the area and know a few folks from the area. A few of my buddies have or had family farms / ranches in the area. Why on earth did you leave there? That's gods country, beautiful, but a little cold in the winter. My elevation is a little lower than it is up at Randolph, but I just finished building a 3 burner forge and yes, It will forge weld quite well here. In fact I need to choke it off just a bit from "full open" to get the flame where I want it. I have used naturally aspirated forges (smaller NC brand) up on Monte Cristo and Avon. (not too far from Randolph) We just used them to get shoes to forging heat for shaping and at high altitudes they do lose a bit, but what is the elevation on top of Monte? I think it is approaching 10K feet. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 20, 2009 Share Posted March 20, 2009 There are pros and cons to either type burner. A gun (blown) burner is easier to build and tune and though you have to retune it every time you turn it up or down it's easy to do. On the down side they're expensive to build and tie you to power though 12v works for a portable. Naturally aspirated burners are a fraction of the cost to build, can be turned up or down with no adjustment at all, neutral to rich is an easy adjustment, you don't need anything but the propane tank. On the down side they are trickier to build and tune, sometimes requiring quite a bit of fiddling to get right. In either case how much heat a burner produces is strictly determined by how much air and fuel it pushes into the furnace. Period. What kind of device that delivers the mix is pretty irrelevant. A gun is less sensitive to back pressure and exterior breezes but a well made ejector will handle either well enough, it just needs to be designed with those in mind. Same with altitude, Building and tuning a burner to run at 6,000 or 12,000' isn't going to be any more difficult than building one to run here at 400'. You aren't going to get good performance running one much out of their intended altitude so add that to the downside list. Noise isn't appreciably different between the types. The major sound is from combustion though there will be some fan noise from a blower it will be well and truly drowned out by the flame. Simply aiming the blower intake away from you makes a huge difference as well. Everything has pros and cons, in this case they're real enough but in neither case deal killers. Frosty Quote Link to comment Share on other sites More sharing options...
Brian D Posted March 20, 2009 Share Posted March 20, 2009 In either case how much heat a burner produces is strictly determined by how much air and fuel it pushes into the furnace. Period. What kind of device that delivers the mix is pretty irrelevant. A gun is less sensitive to back pressure and exterior breezes but a well made ejector will handle either well enough, it just needs to be designed with those in mind. Same with altitude, Building and tuning a burner to run at 6,000 or 12,000' isn't going to be any more difficult than building one to run here at 400'. You aren't going to get good performance running one much out of their intended altitude so add that to the downside list. Well stated Frosty, I think it will not be hard at all to re-tune my burners to run at a higher or lower altitude. I would have to expect a performance shift if I took the tuned burner and run it at a different altitude without re-tuning it. It most likely would be easier and quicker to adjust a forced air burner to run efficiently at a variety of different altitudes. I guess you have to look at your application. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 20, 2009 Share Posted March 20, 2009 Hrisoulas makes a living welding up billets in an aspirated burner at a goodly elevation. I have a gas forge of each type and I can say that the blown burner is much easier to tune---I've tuned it so oxidixing that I was using it for a surface finish---chip off the heavy scale and a lizard skin pattern was left on the dragon's head. I've tuned it so reducing that I could get any scale at all on a blade being heat treated till I took it out of the forge. I can tune it this way for any fuel pressure I choose too, no huffing or back burning either. No problem with strong winds either which I often have with the aspirated burner. (You know it's spring in NM when your neighbor's concrete blocks start blowing into your yard) But I tend to use the aspirated burner forge more often as I generally take a forge camping and for demos and I *NEVER* bet on electicity at the sites. Quote Link to comment Share on other sites More sharing options...
mcraigl Posted March 20, 2009 Share Posted March 20, 2009 Brian, Monte is almost exactly 9000'. If you've forged on top of Monte then I'm definately bowing to your expertise in forge performance at altitude. Basing my experience off of the difference between sea level and 4000', and it's dramatic. Even with a blown forge, at sea level can be so hot you can't even look into the forge, while the same forge at 4000' you can't get to a welding heat. Yea, I know where Hooper is. God's country huh? I guess I can't think of another place in the world I'd have rather grown up, but it's pretty low on my list of places to live now. If you don't own a rance, or work at the coal mines in Kemmerer, there's no way to make a livin'. You can only brand, irrigate, and hay for Deseret Land & Livestock for so long... I got deep roots in the Bear River Valley, but don't miss the winters. I think there's times when the weather in Randolph would make Frosty shiver. Brrr..... Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 20, 2009 Share Posted March 20, 2009 The easy way to make a naturally aspirated burner more altitude adaptable is to design it to run lean at low elevations and use a choke to make the adjustments. Then as you head into the high country you can back off the choke. My old pipe forge would melt mild steel at around 10psi and burns on the rich side. Frosty Quote Link to comment Share on other sites More sharing options...
Brian D Posted March 21, 2009 Share Posted March 21, 2009 God's country huh? I guess I can't think of another place in the world I'd have rather grown up, but it's pretty low on my list of places to live now. If you don't own a rance, or work at the coal mines in Kemmerer, there's no way to make a livin'. You can only brand, irrigate, and hay for Deseret Land & Livestock for so long... I got deep roots in the Bear River Valley, but don't miss the winters. I think there's times when the weather in Randolph would make Frosty shiver. Brrr..... Yea, the winters in that valley make for tough folks, that's for sure. I'm not saying that the same forge will perform the same at very different elevations without some adjustments made to it. But I am saying that you can make necessary adjustments and go to work. Quote Link to comment Share on other sites More sharing options...
Jmichelsen3 Posted March 22, 2017 Share Posted March 22, 2017 I am far from experianced, but I have been doing this as a hobby since I was a kid and avoided gas forges until recently. This was mainly because I was intimidated by the cost buying a burner and didn't have the right parts redily available to make one myself. About a year ago someone gave me a large, and mostly full, propane tank. I decided, due to neighbors complaining about the coal smoke coming from my backyard, to once again look into building a gas forge and happened onto plans for a forced air burner. Long story short, I think I spent 40$ for the regulater, some pipe and fittings and 4 fire bricks that I pretty much wired together. I was able to forge weld the first time I heated her up, which I had pretty much given up as a lost cause with my coal setup. I have since improved/rebuilt my forge (I actually managed to melt my firebricks) but I'm still using the same burner. I'm sure there are plenty of things to recommend venturi type burners, I have used an off the shelf forge with venturi burners and it was great. in my opinion, however, if your a beginner, a die hard do-it-yourselfer, or simply strapped for cash as I was, the forced air burner is the way to go. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted March 31, 2017 Share Posted March 31, 2017 I think Frosty has the correct view. People used to say that naturally aspirated burners did not get hot enough; that view was already outdated when I started building them. eighteen years later it has been repeatedly proved to be complete bunk. Naturally aspirated or fan blown; the only questions are how well the burners and forges are constructed; everything else is personal preference. Quote Link to comment Share on other sites More sharing options...
Latticino Posted March 31, 2017 Share Posted March 31, 2017 One last caveat: I've never seen a successful NA burner run on low pressure (7-9" WG, residential) natural gas. I suppose you could make a really small one, but I doubt it would be very effective. So if you plan on running natural gas you will likely either have to have a special supply from the utility or go with a blown burner. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted April 1, 2017 Share Posted April 1, 2017 It would not matter how small the burner was; it wouldn't work. Quote Link to comment Share on other sites More sharing options...
Frosty Posted April 1, 2017 Share Posted April 1, 2017 Not small, no it wouldn't do for a forge but a large gun burner and residential supply is plenty. You can run larger than a 125,000btu/hr furnace off natural gas. You'd have to be pretty lacking in imagination not to be able to make a forge work on that output. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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